Hydrorefining of petroleum crude oil



- etc.

United States Patent 3,249,530 HYDROREFINING 0F PETROLEUM CRUDE OIL John G. Gatsis, Des Plaines, Ill., assignor to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware No Drawing. Filed Aug. 19, 1963, Ser. No. 303,158 14 Claims. '(Cl. 208264) The present invention relates to the use of a novel catalyst in the hydrorefining of petroleum crude oils, heavy vacuum gas oils, heavy cycle stocks, crude oil residuum, topped crude oils, etc. More specifically, the present invention involves a process for hydrorefining heavy hydrocarbon charge stocks to effect the removal of nitrogen and sulfur therefrom, and is advantageous When employed for the destructive removal of organo-metallic contaminants and particularly the conversion of pentaneinsoluble hydrocarbonaceous material.

Petroleum crude oil, and the heavier hydrocarbon fractions and/or d-istillates obtained therefrom, particularly heavy vacuum gas oils and topped crudes, contain-ni trogenous and sulfurous compounds in large quantities. In addition, petroleum crude oils generally contain det rimental quantities of organo-metallic contaminants which exert deleterious effects upon the catalyst utilized in various processes to which the crude oil, topped crude oil, or heavy hydrocarbon fraction may ultimately be subjected. The more common of such metallic contaminants are nickel and vanadium, often existing in concentrations in excess of 50 p.p.m., although other metals including iron, copper, etc., may be present. Although metallic contaminants, existing as oxide or sulfide scale, may be removed, at least in part, by a relatively simple filtering technique, and water-soluble salts are at least in part removable by washing and a subsequent dehydration procedure, a much more severe treatment is required to effect the destructive removal of organo-metallic compounds, such -as metal porphyrins, particularly to the degree necessary to produce a crude oil or heavy hydrocar-bon fraction which is suitable for further processing.

In addition to organo-metallic contaminants, crude oils contain greater quantities of sulfurous and nitrogenous compounds than are generally found in lighter hydrocarbon fractions such as gasoline, kerosene, light gas oil, For example, a Wyoming sour crude, having a gravity of 23.2 API at 60 F., contains about 2.8% by weight of sulfur and 2700 p.p.m. of total nitrogen. A crude tower bottoms, having a gravity of 14.3 API, contains 3.08% by weight of sulfur, 10.93% by weight of pentane-insolubles, 3830 p.p.m. of nitrogen and 85 p.p.m. of metallic contaminants. The nitrogenous and sulfurous compounds are converted, upon being subjected to a catalytic hydrorefining process, into hydrocarbons, ammonia and hydrogen sulfide; the reduction in the concentration of the organo-metallic contaminants is not as easily achieved, and to the extent that the same no longer exert a detrimental effect, particularly in regard to further processing of the crude oil. When a hydrocarbon charge stock containing metals in excess of about 3.0 p.p.m., is subjected to a cracking process for'the purpose of producing lower-boiling components, the metals become deposited upon the catalyst employed, steadily increasing in quantity until such time as the composition of the catalytic composite is changed to the extent that undesirable results are obtained.

However, in addition to the foregoing contaminating influences, crude oils and other heavier hydrocarbon frac tions contain excessive quantities of pentane-insoluble material. For example, the Wyoming sour crude described above consists of about 8.3% by weight of pentane-insolu-b-le asphaltenes. These are hydrocarbonaceous com- Patented May 3, 1966 "ice and surfaces thereof from the material being processed.

The conversion of these pentane-insoluble asphaltenes is that function of the catalyst most diflicult to achieve, and not withstanding an acceptable degree of elimination of the other contaminants, the liquid product efiluent may contain a detrimental amount of this material.

The object of the present invention is to provide a more efficient process for hydrorefining heavier hydrocarbonaceous material, and particularly petroleum crude oil, utilizing an unsupported catalyst prepared in a particular manner. The term hydrorefining, as employed herein, connotes the catalytic treatment, in an atmosphere of hydrogen, of a petroleum crude oil, or a hydrocarbon fraction or distillate for the purpose of eliminating and/ or reducing the concentration of the various contaminating influences previously described. As hereinabove set forth, metals are generally removed from the charge stock by deposition of the same on the catalyst employed. This increases the amount of catalyst, actively shields the catalytica-lly active surfaces and centers from the material being processed, and thereby virtually precludes the utilization of a fixed-bed catalyst system for processing such contaminated crude oil. Various moving-bed processes, employing catalytically active metals deposited upon a carrier material consisting, for example, of silica and/or alumina, or other refractory inorganic oxide materials, are extremely erosive, causing plant maintenance to become difiicult and expensive. teaches the preparation of a colloidally dispersed, unsupported catalytic material useful in a slurry process, which catalytic material will not effect extensive erosion or corrosion of the reaction system. The present process yields a liquid hydrocarbon product which is more suitable for further processing without experiencing the difficulties otherwise resulting from the presence of the foregoing contaminants. The process of the present invention is particularly advantageous for effecting the conversion of sulfur-ous, nitrogenous and the organo-metallic contaminants Without significant product yield loss, while simultaneously converting a substantial quantity of pentane-insoluble material into pentane-soluble liquid hydrocarbons.

In a 'broad embodiment, the present invention relates to a process for hydrorefining a hydrocarbon charge stock which comprises admixing said charge stock with at least one heteropoly acid selected from the metals of Group VI-B having an atomic number greater than 24, heating the resulting mixture at a temperature less than about 310 C. and for a time sufficient to form a colloidal dispersion of said heteropoly acid, combining the colloidal dispersion with an iodine-containing compound, reacting the same with hydrogen at a temperature in excess of about 225 C. and at a pressure greater than about 500 pounds per square inch gauge, and recovering a hydrorefined liquid product.

Another broad embodiment of the present invention encompasses a process for hydrorefining a petroleum 2 atomic number greater than 24, heating the resulting mix- The present invention ture at a temperature less than about 310 C. and for a time sufiicient to form a colloidal dispersion of said heteropoly acid, combining the colloidal dispersion with iodoform, reacting the same withhydrogen at a temperature in excess of about 225 C. and at a pressure greater than about 500 pounds per square inch gauge, and recov- 'ering said crude oil substantially free from pentane-insoluble asphaltenes.

, A more limited embodiment of the present invention involves a process for hydrorefining a petroleum crude oil containing pentane-insoluble asphaltenes which comprises admixing said crude oil with phosphomolybdic acid, heating the resulting mixture at a temperature less than about 310 C. and for a time sufficient to form a colloidal dispersion of said phosphomolybdic acid, reacting the colloidal dispersion and a metallic iodide selected from the metals of Group II of the Periodic Table with hydrogen at a temperature within the range of from about 225 C. to about 500 C. and at a pressure of from about 500 to about 5000 pounds per square inch gauge, and recovering said crude oil substantially free from pentaneinsoluble asphaltenes.

From the foregoing embodiments, it is noted that the method of the present invention involves the preparation of a catalyst utilizing metals selected from Group VI-B of the Periodic Table. Reference is herein made to the Periodic Chart of the Elements, pages 448 and 449, 43rd edition of Handbook of Chemistry and Physics. It is further noted that the metals from Group VIB, namely molybdenum and/or tungsten, have an atomic number greater than 24. It has been found that heteropoly acids of chromium, in addition to other chromium complexes, upon decomposition within the hydrocarbon charge stock, do not yield acceptable economical results, and particularly with respect to the conversion of the pentane-insoluble fraction and the organo-metallic compounds such as the nickel and/or vanadium porphyrins. Furthermore, the decomposition of such chromium complexes is effected above about 310 C., resulting in premature thermal cracking of thecrude oil. Briefly, the catalyst is preferably prepared by dissolving heteropoly molybdic acids and/ or heteropoly tungstic acids, such as phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid and silicotungstic acid in an appropriate solvent such as alcohols containing up to and including about ten carbon atoms per molecule. Thesolution is added to the petroleum crude oil and the mixture distilled with stirring, at a temperature less than about 310 C., to remove the solvent and form a colloidally dispersed catalyst sus pended within the petroleum crude oil. The quantity of the heteropoly acid employed is such that the colloidal suspension, or dispersion, which results upon removal of the solvent, comprises from about 1.0% to about 10.0%

by Weight, calculated, however, as the elemental metal.

' Suitable heteropoly acids, selected from the metals of Group VI-B having an atomic number greater than 24 include phosphomolybdic, phosphotungstic acid, silicomolybdic acid, silicotungstic acid, and mixtures thereof including phosphomolybdic acid-phosphotungstic acid, etc. The process is etfected, as hereinafter set forth'in specific examples, by initially dissolving the desired quantity of the heteropoly metallic acid, such as phosphomolybdic acid, in the hydrocarbon charge stock. When the phosphomolybdic acid is initially dissolved in an alcohol containing up to and including about ten carbon atoms per molecule, the contaminating influences, with the exception of asphaltenes, with the petroleum crude oil are removed to the extent that the future processing of such crude oil no longer incurs the detrimental eifects otherwise resulting from the presence of these contaminating influences. As previously set forth, the conversion of asphaltenes is most difiicult to achieve; further, as the concentrations of the other contaminants increases, the degree of conversion of the asphaltenes is lessened. Typical of the alcohols suitable for use in preparing the solution of the desired heteropoly metallic acid include isopropyl alcohol, isopentyl alcohol, methyl'alcohol, amyl alcohol, mixtures thereof, etc. The mixture of the alcohol solution of the phosphomolybdic acid and the petroleum crude oil is heated at a temperaturebelow about 310 C. for the purpose of distilling the alcohol, leaving the phosphomolybdic acid as a colloidal dispersion within the crude oil. Temperatures above about 310 C. tend to result in premature cracking reactions whereby the effectiveness to convert pentane-insoluble asphaltenes becomes adversely affected. It is further noted, from the foregoing embodiments, that the colloidal dispersion of the heteropoly metallic acid and charge stock is admixed with an iodine-containing compound prior to being introduced into the reaction zone to be reacted with hydrogen therein. For the purpose of distilling the solvent employed in initially preparing the colloidal dispersion, it is preferred to add the iodine-containing compound after the solvent is removed; in this way, the heavy hydrocarbonaceous charge stock will contain the desired quantity of iodine while being processed at reaction conditions.

The iodine-containing compound is employed in an amount within the range of about 0.05% to about 5.0% by weight, calculated on the basis of the quantity of charge stock, and as the element. Iodine, hydrogen iodine and iodoform are the particularly preferred iodine-containing compounds utilized in combination with the desired heteropoly acid, although metallic iodides will yield acceptable results under proper operating conditions. Suitable metallic iodides are those selected from'the metals of Group II of the Periodic Table, and include, therefore, beryllium, magnesium, calcium, strontium, barium, zinc, cadmium,'mercury, mixtures of tWo or more, etc. These metallic iodides may also be employed in combination with iodoform, iodine, and/or hydrogen iodine, maintaining the concentration of iodine within the aforesaid range. The colloidal dispersion is then passed into a suitable reaction zone maintained at a temperature within the range of from about 225 C. to about 500 C. and under a hydrogen pressure within the range of about 500 to about 5000 p.-s.i.g. The process may be conducted in a batch-type procedure or in an enclosed vessel through which the colloidal suspension is passed; When effected in a continuous manner, the process may be conducted in either upward flow or downward flow. The normally liquid hydrocarbons are separated from the total reaction zone eflluent by any suitable means, for example, through the use of a centrifuge or settling tanks, at. least a portion of the'resulting catalystcontaining sludge being combined with fresh petroleum crude "oil, and recycled to the reaction zone. In order to maintain the highest possible degree of catalytic activity, it is preferred that at least a portion of the catalyst-containing sludge be removed from the process prior to combining the remainder with fresh crude oil. The precise quantity of the 'catalystecontaining sludge removed from the process will be dependent upon the desired degree of contaminant removal. However, it is further desirable to add a quantity of fresh phosphomolybdic acid and the iodine-containing compound to the petroleum crude oil 1n order to compensate for that quantity of molybdenum,

calculated as the elemental metal, removed from thecatalyst containing sludge.

As hereinabove set forth, the vhydrorefining catalyst utilized in the process of the present invention, exists as a colloidal dispersion within the hydrocarbonaceous charge stock being subjected to reaction with hydrogen. Thus, the catalyst is a colloidally dispersed heteropoly acid selected from the group which has been previously described. The catalytic action exhibited by the hetero-.

poly acid is supplemented, in a synergistic manner,

through the utilization of an iodine-containing compound such as iodine, hydrogen iodine, iodoform and metallic iodides from the metals of Group II of the Periodic Table. As hereinafter indicated by specific example, the

utilization of a combination of the iodine-containing compound and the heteropoly acid results in a significantly greater degree of contaminant removal than when either one is employed in the absence of the other. Surprisingly, there exists the synergistic effect that the greater degree of decontamination of the charge stock can be effected at a significantly lower temperature level. Of itself, as recognized by those possessing skill within the art of petroleum refining operations, this one simple factor affords a great degree of economic benefit in the design and operation of the unit. For example, by permitting operation at a lower temperature level, the residence time or space velocity, or charge stock to catalyst weight ratio, can be economically adjusted to achieve the same degree of decontamination than when either compound is utilized in the absence of the other. The deposition of coke and other carbonaceous material is lessened, and the degree of thermal cracking, resulting in the production of gaseous light paraffins such as methane, ethane and propane, is significantly minimized.

These and numerous other advantages will be readily apparent to those having knowledge of petroleum refinery operations and the economic considerations involved therewith.

The following examples are given to illustrate the process of the present invention and the effectiveness thereof in converting pentane-insoluble asphaltenes into pentane-soluble, lower-boiling liquid hydrocarbon products.

EXAMPLE I The crude oil employed to illustrate the benefits afforded through the utilization of the present invention was a crude tower bottoms having a gravity, AP-I at 60 F., of 14.3, containing about 3.0% by weight of sulfur, 3830 ppm. of nitrogen and consisting of 10.93% by weight of pentane-insoluble asphaltenes. These and other analyses of the charge stock are indicated in the following table.'

Crude tower bottoms analysis Gravity, ABI 60 F. 14.3 Volume distilled F.:

Sulfur, wt. percent 3.08 Total nitrogen, p.p.rn. 3830 Metals contamination, p.p.rn. 91 Pentane-insolubles, wt. percent 10.93

A colloid-a1 dispersion of 30 grams of phosphomolybdic acid was prepared by initially dissolving the phosphomolybdic acid in 400 grams of isopropyl alcohol and filtering to remove small traces of insoluble material. 1000 grams of the crude tower bottoms was placed in a two-liter reaction flask containing a vibromix stirrer, and the isopropyl alcohol solution added thereto in dropwise fashion. The temperature of the contents of the twoliter flask was maintained at 130 C. such that the alcohol was distilled while the solution was added to the crude tower bottoms.

200 grams of the colloidal dispersion were placed in an 1800-milliliter, rocker-type autoclave, and pressured to 100 atmospheres with hydrogen. The autoclave was heated to a temperature of 350 C., and maintained at this temperature level for a period of 5 hours. The contents of the autoclave were cooled to room temperature removed therefrom and subjected to centrifugal action to separate the normally liquid product from the catalystcontaining sludge. In this instance, the normally liquid product indicated a gravity, API at 60 F., of 16.4 and contained 1.54% by weight of pentane-i-nsoluble asphaltenes.

For this portion of the example, the charge stock was a Wyoming sour crude oil having a gravityof 6 28.9 API at 60 F. contained 0.97% by weight of pentane-insoluble asphaltenes.

Notwithstanding the lesser degree of contamination of the sour crude oil, as well as the more severe operating temperature, it will be noted that the degree of Crude tower bottoms in an amount of 200 grams and 2 grams of iodoform were placed in the 1800 milliliter rocker-type autoclave, pressured to atmospheres with hydrogen and heated to a temperature of 350 C., being maintained at this level for a period of 5 hours. Upon separation of the liquid product efiluent from the sludge,

the former was found to have a gravity, API at 60 F.,. of 20.6, and contained 4.79% by weight of pentane-in-- soluble asphaltenes.

Crude tower bottoms in an amount of 200 grams and 2 grams of iodoform were reacted with hydrogen at a temperature of 375 C., for a period of 5 hours, and the liquid product effluent indicated a gravity, API at 60 F., of 23.2, and contained 4.17% by weight of pentaneinsoluble asphaltenes.

This example illustrates the fact that the use of iodoform, in the absence of the phosphomolybdic acid, although resulting in a substantial conversion of the tower bottoms into lower-boiling hydrocarbon products, obviously does not result in an acceptable degree of conversion of the pentane-insoluble asphaltenes.

EXAMPLE III 20 0 grams of the colloidal dispersion of phosphomolybdic acid in the crude tower bottoms, described in conjunction with the foregoing Example I, and 2 grams of iodoform were placed in the 1800 milliliter rocker-type autoclave, pressured to 100 atmospheres with hydrogen and heated to a temperature of 375 C., being maintained atthis level for a period of 5 hours. Following separation of the contents into the catalyst-containing sludge and normally liquid hydrocarbons, the latter was found to have a gravity, API at 60 F., of 26.5, and contained 0.18% by weight of pentane-insoluble asphaltenes. This example indicates the synergistic effect resulting through the utilization and the combination of the phosphomolybdic acid and iodoform. As indicated by the data presented in Example II, it would be presumed that the addition of iodoform to the phosphomolybdic acid colloidal dispersion would not have the effect of decreasing the concentration of pentane-insoluble asphaltenes in the liquid product eflluent; at best, it might be expected that there would be no effect whatsoever. To the contrary, it has been shown that the addition of the iodoform significantly improves the catalytic action exhibited by the phosphomolybdic acid.

The foregoing specification and examples indicate the method of the present invention, and illustrate the benefits to be afforded through the utilization thereof. It is not intended that the present invention be limited unduly to the reagents, operating conditions and/or concentrations employed therein, beyond the scope and spirit of the appended claims.

I claim as my invention:

1. A process for hydrorefining a hydrocarbon charge stock which comprises admixing said charge stock with at least one heteropoly acid containing a metal of Group VI-B having anatomic number greater than 24, heating the resulting mixture at a temperature less than about 310 C. and for a time sufiicient to form a colloidal dispersion of said heteropoly acid, commingling iodine with the colloidal dispersion, reacting the resultant mixture with hydrogen at a temperature in excess of about 225 C. and at a pressure greater than about 500 p.s.i.g., and recovering a hydrorefined liquid product.

'2. The process of claim 1 further characterized in that said mixture is reacted with hydrogen at a temperature within the range of from about 225 C. to about 500 C. and under a pressure of from about 500 to about 5000 .s.1.g. p 3. The process of claim 1 further characterized in that said heteropoly acid comprises phosphomolybdic acid.

4. The process of claim 1 further characterized in that said heteropoly acid comprises phosphotungstic acid.

5. A process for hydrorefining a petroleum crude oil containing pentane-insoluble asphaltenes which comprises admixing said crude oil with at least one heteropoly acid containing a metal of Group VI-B having an atomic number greater than 24, heating the resulting mixture at a temperature less than about 310 C. and for a time sulficient to form a colloidal dispersion of said heteropoly acid, combining the colloidal dispersion with iodoform, reacting the resultant mixture with hydrogen at a temperature in excess of about 225 C. and at a pressure greater than about 500 p.s-.i.g., and recovering said crude oil substantially free from pentane-insoluble asphaltenes.

6. The process of claim 5 further characterized in that said heteropoly acid comprises phosphotungstic acid.

7. The process of claim 5 further characterized in that said heteropoly acid comprises silicomolybdic acid.

8. The process of claim 5 further characterized in that said heteropoly acid comprises silicotungstic acid.

9. A process for hydrorefining a petroleum crude oil containing pentane-insoluble asphaltenes which comprises admixing said crude oil with phosphomolybdic acid and iodoform, heating the resulting mixture at a temperature less than about 310 C. and for a time sufiicient to form a colloidal dispersion of said phosphomolybdic acid, reacting the colloidal dispersion with hydrogen at a temperature within the range of about 225 C. to about 500 C. and at a pressure of from about 500 to about 5000 p.s.i.g., and recovering said crude oil substantially free from pentane-insoluble asphaltenes.

10. A process for hydrorefining a petroleum crude oil containing pentane-insoluble asphaltenes which comprises admixing said crude'oil with phosphomolybdic acid, heating the resulting mixture at a temperature less than about 310 C. and for a time sufficient to form a colloidal dispersion of said acid, combining the colloidal dispersion with iodoform, reacting the resultant mixture with hydrogen at a temperature in excess of about 225 C. and at a pressure greater than about 500 p.s.i.g., and recovering said crude oil substantially free from pentane-insoluble asphaltenes.

11. A process for hydrorefining a hydrocarbon charge stock which comprises admixing said charge stock with phosphomolybdic acid, heating the resulting mixture at a temperature less than about 310 C. and for a time suflicient to form a colloidal dispersion of said acid, cornmingling iodoform with the colloidal dispersion, reacting the resultant mixture with hydrogen at a temperature in excess of about 225 C and at a pressure greater than about 500 p.s.i.g., and-recovering a hydrorefined liquid.

product. 12. A process for hydrorefining a hydrocarbon charge stock which comprises subjecting said charge stock to reaction with hydrogen in admixture with iodine and a colloidal dispersion of at least one heteropoly acid containing a metal of Group VIB having an atomic number greater than 24 at a temperature in excess ofabou-t 225 C. and at a pressure greater than about 500 p-.s.i.g., and recovering a hydrorefined liquid product.

13. The process of claim 12 further characterized in that said iodine is introduced to the charge stock in the form of iodoform.

14. A process for hydrorefining a hydrocarbon charge stock which comprises subjecting said charge stock to reaction with hydrogen in admixture With iodoform and a colloidal dispersion of phosphomolybdic acid at a temperature in excess of about 225 C. and at a pressure greater than about 500 p.s.i.g., and recovering a hydrorefined liquid product.

References Cited by the Examiner UNITED STATES PATENTS 3,165,463 1/1965 Gleim et al. 208-264 3,166,494 1/1965 Gatis et a1. 208264 PAUL M. COUGHLAN, Primary Examiner.

S.-P. JONES, Assistant Examiner. 

1. A PROCESS FOR HYDROREFINING A HYDROCARBON CHARGE STOCK WHICH COMPRISES ADMIXING SAID CHARGE STOCK WITH AT LEAST ONE HETEROPOLY ACID CONTAINING A METAL OF GROUP VI-B HAVING AN ATOMIC NUMBER GREATER THAN 24, HEATING THE RESULTING MIXTURE AT A TEMPERATURE LESS THAN ABOUT 310*C. AND FOR A TIME SUFFICIENT TO FORM A COLLOIDAL DISPERSION OF SAID HETEROPOLY ACID, COMMINGLING IODINE WITH THE COLLODAL DISPERSION, REACTING TH RESULTANT MIXTURE WITH HYDROGEN AT A TEMPERATURE IN EXCESS OF ABOUT 225*C. AND AT A PRESSURE GREATER THAN ABOUT 500 P.S.I.G., AND RECOVERING A HYDROREFINED LIQUID PRODUCT. 